690815381 has 4 divisors (see below), whose sum is σ = 690930732. Its totient is φ = 690700032.

The previous prime is 690815341. The next prime is 690815393. The reversal of 690815381 is 183518096.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 409414756 + 281400625 = 20234^2 + 16775^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690815381 is a prime.

It is a super-2 number, since 2×690815381² = 954451781252350322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (690815311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48170 + ... + 60843.

It is an arithmetic number, because the mean of its divisors is an integer number (172732683).

Almost surely, 2^690815381 is an apocalyptic number.

It is an amenable number.

690815381 is a deficient number, since it is larger than the sum of its proper divisors (115351).

690815381 is a wasteful number, since it uses less digits than its factorization.

690815381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115350.

The product of its (nonzero) digits is 51840, while the sum is 41.

The square root of 690815381 is about 26283.3670027263. The cubic root of 690815381 is about 884.0035305750.

It can be divided in two parts, 690815 and 381, that added together give a palindrome (691196).

The spelling of 690815381 in words is "six hundred ninety million, eight hundred fifteen thousand, three hundred eighty-one".